The present invention relates to a piston pump. More particularly, it relates to a high pressure piston pump particularly for aggressive and/or abrasive and sometimes hot flow medium.
Piston pumps of the above-mentioned general type are known in the art. A known piston pump has a valve through-chamber extending from a suction valve to a pressure valve, a working chamber in which a piston reciprocates, and a force-transmitting chamber connecting the valve-through chamber with the working chamber and accommodating a force transmitting medium which transmits the energy stroke of the piston to the flow medium and at the same time separates the flow medium from the piston.
In such a piston pump the force transmitting chamber is formed by a substantially S-shaped force-transmitting conduit with a vertical section whose inner chamber corresponds at least the magnitude of the piston displacement. A supply line for the force-transmitting medium is located in the vicinity of the working chamber, and the force-transmitting medium fills the force-transmitting chamber at the end of the pressure stroke of the piston, substantially to the lower part of the vertical section. The loss of the force-transmitting medium is replenished by respective supply. The working chamber and the piston are provided with shields for separating the valve through-chamber and the flow medium.
Pumps having force-transmitting chambers can be advantageously utilized for many substances, instead of diaphragm pumps. They have special advantages in the cases when they supply a liquid which must be separated from the seals of the piston, for example a plunger piston, because the liquid or its components provide for solvent or abrasive action. The chemical industry makes the requirement of the utilization of such liquids in extensive range. These liquids include, for example, carbamate, chemical liquids such as fatty alcohols or the like with admixed catalysts, suspensions and so on. As a force-transmitting medium, a liquid is utilized which does not mix with the flow medium.
The known pumps of the above-mentioned type have relatively long conduits and units which are separated from one another, whereby these pumps are bulky and heavy which make difficult their utilization. Further, the force-transmitting conduits, particularly in high pressure pumps, are subjected to the action of alternative forces and thereby material fatigue can take place which is facilitated by the angled shape of the force-transmitting conduit. Moreover, it has been noticed during flow of the hot flow medium that the heat load of the force-transmitting conduit undesirably affects its strength and resistance.